Process of making indigo.



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NIKODEM CARO, or OHARLOTTENBURG,GERMANY, ASSIGNOR TO soerE'rA GENERALE PER LA CIANAMIDE, or none, ITALY. 1

PROGESS OF. MAKING INDIGCi.

No. season.

Specification of Letters Patent.

Patented July 23,1907.

App catio filed September 1906. Serial No. 333,66.

To 'all whom it may concern:

Be it known that I, NIKODEM Case, a subject of the Emperor of Germany, residing at Charlottenburg, near Berlin, Germany, have invented certain new and useful Improvements in a'Precess of Producing Indigo, of which the following is a specification.

My invention relates to the production of indigo synthetically, and is more especially concerned with the production of indigo from phenyiglycin or its derivatives by the action upon it of a suitable alkali cyanamid.

The object of my invention is to increase the yield of indigo and I attain this object primarily by obviating the detrimental rise in temperature which is consequent to the heretofore practiced'method.

It is already known, that in the action of a mixture of sodium amid and sodium cyanid upon phenylglycin,

its alkali salts or other derivatives, such as phenylglycin-carbonic acid etc., reaction products, which give indigo by oxidation in the air, are producedf Experiments have shown, that the formation of these products is due partly to the direct action of the sodium amid, but partly also to the action of the so dium cyanamid resulting from the sodium amid and the sodium cy'anid. It has further appeared; that the action of shch a mixture of sodiuin amid and sodium cyanid, partly because of the action of sodium cyanid upon sodium amid and partly because of the action of sodium amid upon the phenylglycin, is accomplished ,sodium amid. In such a process, however," it is necessary to mix the disodiurn cyanamid which melts at a high temperature, with a flux having a lower melting point, and which is, at the eametime, isiert to the phenylglycin omits derivative, in order to effect the reaction at a lower temperature and enable its regulation. An alkali cyanid, such as sodium cyanid, an-

swers these requirements as a flux.

As an example of'my invention, one part of disodium cyanamidwith five parts of sodium cyanid may be heated up to the melting point in an iron crucible and phcnylglycin or its sodium salt added. The formation of an indigo yielding substance then takes place without further heating, and the reaction proceeds almostquantitatively.

It is most suitable to proceed by putting equal parts by weight of the above described mixture of 'disodiuln cyanamid and sodium cyanid and phenylglycin or 5$ phenylsodjum in a crucible heated up to 30400 C1, then leaching out'the cooled fused mass and blowing a current of oxidizing gas, such as air, through the solution obtained.

Indigo is produced almostquantitatively in this way, 6i) and may be separated out and purified 'in the usual manner. Instead of using phenylglycin' and phenylglycin sodium, one may employ to equal advantagev phenylglycin-carbonic acid and its salts, and all such equivalents are intended to be covered by the term .65 phenylglycin as used inthe claims. 7 I 1..

Since the dialkali cyanamid can beobtained d ireetly from carbid in a simple manner, the process: forming the subject oi the present application provides a further important technical advantagewith respect to the obtaining'of this particular raw material. 7

Since' in many cases derivatives of phenylglycin such as those mentioned in this specification can be I employed as equivalents of phenylglycin, I shall-refer in the claims to phenylglycin only, it being under- '75 stood that its deri'vativesare considered by me as equivalents thereof.

Having thus described my inventionfthefollowing is ,what I claim as myinvcntion, and desire to secure by Letters Patent: I

1, The process of producing an indigo yielding substance, which consists in reacting upon plienylglycin, with an alkali cyunamid and :1 tlux. 4

2. The process of producing an indigo yielding sub, stance, which, consists in reacting upon plienylglycln, with an alkali cyainunid and a flux inert to the phenylglycln.

3. The process of producing an indigo yielding substance, which consists in reacting upon phenylglycln, with an alkali cyunamid and a flux inert to the phenylgylcln and fusing at a lower temperature than'the alkali cyanum'id.

4. The process oliproduclng an indigo yielding substance, which. consists in reacting upon phenylglycin, with an alkali cyanamld and a flux consisting of an alkali cyanld. v 5

5. The process of producing an indigo ylelding' substance, which consists in reacting upon 'phenylglycin with .an alkali cyunamid and a flux consisting 01 sodium cyanld, 61 The process of producing an ludlgo"yleldlng sub stance, which consists in reacting upon. phenylglycin'; with '100 u cyanamld of sodium anda flux. r

7. The process of producing an indigo yielding substance, which consists in reacting upon phenylglycln, with u cyanumid of sodium and a flux inert to the phenylglycin.

S. The process of producing an indigo yielding 'sub- 105 stance, wlilcli ,consists in reacting upon plienylglycin, with a cyanamid of sodium and u flux inert to the phenylglycln and having a melting temperature lower than the cyana mid.

stance, which consists in reacting upon phenylglycin, with a cynnamid ofsodinin and n flux consisting of sodium cyzmid.

11. The process of producing an indigo yielding suh stance, which consists in reacting upon phenylglycin, with disodium cynnzunid and u flux 12. The process of producing an indtizo yielding suhstance, which consists in reacting nponphenylglycin, with disodium eynnnmid and a fiux inert to the phenylglycin.

The process of producing an indigo yielding snh stance, which consists -in reacting upon phcnylglycin, with disor liuni eynnun id jmd :rfiux inert to the phenylglycin and having 'a lower melting temperature than the cyanon'iid.

14. The processIof producing an indigo yielding suhstance, which consists in reacting upon phenylglycin with disodiuin cyannmid and a flux consisting of' an alkali cyn nid. v

15. The process of producing on indigo yiolding'snbstance, whichconsists in reacting upon phony]; ycin, with 'a dialkali cyanamid'andn flux.

1G. The process of" producing an indigo-yielding sul) stiincejwhich c nsilsfs in reacting u'po'n phenylglvz n, with nd'ulkali cy'anamid and-:1 flux inert t'othc phony 171 Tli e piioccc Ioi producing. an indigo yielding suh stance, which consists in reacting-upon phenylglycin, with a dinlkali cyanamid and a flux inert to the phenylglycin and having a lower melting temperature than the cydna mid.

18. The process of producing an indigo yielding sub stance, which consists in reacting upon phenylglycin, with a dialkali cynnamid and n iiux consisting of an alkali cya nid a 1 1D. The process of producing an indigo yielding substance, which consists in. reacting upon phenylglycin, with :1 dinlknlicvnnumid and :1 flux consisting of sodium cyanid.

20. The hercindescrihed process of producing indigo, which consists in heating :1 mi ture of disodium cyannmid, 

